The Book of Liberation is perhaps the most enigmatic philosophical text from ancient India. Presented as the teachings of Bhishma as he lies dying on the battlefield, after the epic war between the Pandavas and Kauravas, it was composed by unknown authors in the last centuries BCE, during the early period of world-renunciation, when peripatetic sages meditated under trees and practiced austerities in forest groves, and wandering sophists debated in the towns and cities. There has been no time like it before or since: such freedom of thought and expression is unparalleled in the...